Mechanical and electronic properties of superhard Re B2

Abstract

Considering the effect of spin-orbit coupling, we have studied the equation of state, elastic properties, and the electronic structures of Re B2 by first-principles plane-wave basis pseudopotential calculations. Our calculated results show that Re B2 has high bulk modulus (356 GPa), large shear modulus (293 GPa), and great elastic constant c44 (284 GPa), and thus support that Re B2 is ultraincompressible and a potentially superhard material. Besides the compact crystal structure, the electronic mechanisms of its hardness can be understood from the highly directional covalent bonds and the optimal filling of the bonding states. © 2007 The American Physical Society.